Interstellar Flight in Context: A Bet Already Won?

byPaul GilsteronSeptember 23, 2008

The staggering difficulty posed by interstellar flight pushes us to imagine alternatives to today’s technologies. Using conventional rocketry we’re forced to amass so much propellant that the craft we want to send seem impossible to build, even if we could afford the vast fuel bill. A jacked up rocket engine is, of course, nothing but an old technology pushed to its extreme imaginative limits. And you could sense the constraints in that vision at the recent Joint Propulsion Conference in Hartford (CT), discussed not only in these pages but also here by Ray Villard.

I mention Villard’s comments because while I focused on Robert Frisbee’s antimatter rocket concepts in my Centauri Dreamspost, Ray tackles the much broader question of how we place technologies within the context of scientific progress. The news director for the Hubble Space Telescope, Villard is well versed in the rewards and challenges of spaceflight, but he’s nonplussed with some of the reaction to the Hartford conference, much of it focused on the apparent impossibility of interstellar flight. Are these prognostications of doom accurate or do they indicate, as he opines, a simple ‘failure of imagination’?

For extrapolating from today into tomorrow often leads to dead ends. If rocket science doesn’t work, one possibility is to change the paradigm, leaving the fuel behind in the Solar System, or harvesting it along the route. The first alternative evokes beamed propulsion concepts including laser- and particle beam-pushed sails. The latter reminds us of Robert Bussard’s interstellar ramjet, a concept that now seems impractical (such devices seem to generate enough drag to make them function better for braking than acceleration), but one which has never been entirely abandoned. And then, as Villard notes, there are star drives:

The idealized “star drive” uses fundamental properties of matter and space-time to create propulsive forces anywhere in space without the need for carrying fuel. The idea of somehow tapping energy from the vacuum of space may be a little less crazy now. That’s because astronomers have discovered that the universe is dominated by “dark energy” which is stretching the fabric of space at an ever-faster rate. This has rattled our confidence in knowing the true underpinnings of modern physics.

All of which is the reason we keep such a close eye on dark energy research in these pages, for if there is a force of nature that may lead to our re-writing the textbooks, this is it, and its potential uses in propulsion (assuming we advance to the point we can harness it) are mind boggling. We’re at the very edge of speculation here, but at the same time, much that we now take for granted was once equally imponderable.

My guess is that the first interstellar mission, which I assume will be a robotic science probe, will fly with technologies that are as hard for us to imagine as (this is Villard’s phrase) ‘a Roman archer trying to imagine a military laser cannon.’ Tibor Pacher, my erstwhile opponent in the interstellar bet on the Long Bets site, doubtless agrees, but he may think that potential breakthroughs are closer than I do, or he wouldn’t be putting his money behind an interstellar launch as early as 2025. The great unknown here is the pace of computer technology and the possibility of vastly accelerated change.

Because people can vote on Long Bets, I hope you’ll drop by to cast yours. So far the ballots are running 23 to 7 in my favor, but I’m quick to note that neither of us will be collecting any money on New Year’s Eve, 2025. That night I hope to meet with Tibor either in northern Germany or Budapest to open a bottle of Champagne as we toast the victor (Tibor, I lean toward Pol Roger, and I suspect you’ll be buying). The funds that have accumulated interest through the intervening years will go either to the Tau Zero Foundation or SOS-Kinderdorf International, both good causes aimed at enhancing humanity’s future.

In the midst of all this interstellar musing, in came an e-mail from the SETI League’s Paul Shuch, opining that the bet has already been won and, moreover, that Tibor is the victor! Let me quote Paul:

I would argue that the first interstellar missions have already launched, and that (with only a little imagination) they meet the conditions of the bet. They are not spacecraft, but rather streams of photons. Think about it: interstellar microwave transmissions probe other civilizations’ interest in dialog, and pass numerous stars, thus are “flyby probes” in a sense. They are transmitted specifically for the purpose of reaching other solar systems. They have been “launched” (transmitted) several times from Earth, which is clearly within the orbit of Neptune. Some have conveyed scientific information about Earth, which satisfies the condition that they “deliver data for at least one scientific measurement.” They travel at the speed of light, so within the 2,000 year mission duration, will reach stars within 2,000 LY of our own Sun. And they are widely supported by the public, as witness the large number of humans who have submitted messages to the various projects that beam them into space. So, congratulations Tibor, you win!

Remind me not to play poker with Paul, who in the following e-mail exchange added that his argument was a bit of a Kobayashi Maru — a more or less no-win situation, for those of you not familiar with Star Trek lore. The key word here is ‘deliver,’ for now that I read through our Long Bets terms, I see that the operative sentence is ‘As a minimum requirement for the mission the spacecraft shall be capable to deliver data for at least one scientific measurement.’ Now, slapping forehead with palm, I wish Tibor had written (and I had agreed to) ‘return’ instead of ‘deliver’ data! Although I’m not conceding, I do invite Paul to join us for Champagne in 2025, and maybe Ray Villard can join us as well.

Comments on this entry are closed.

ljkSeptember 23, 2008, 10:03

“Man must rise above the Earth – to the top of the atmosphere
and beyond – for only thus will he fully understand the world
in which he lives.” – Socrates

Paul Shuch may be right about the letter of the bet, but I think you and Tibor will both agree that his argument is not within the spirit of the bet. Keep the terms of the bet as you intended them, not as you wrote them.

I’m not sure Shuch’s arguments pass muster. It’s a cute argument. but obviously not true to the spirit of the original bet.

I agree that if we reach the stars (which I believe we will, one day) then it will be with technologies we are barely beginning to imaging today. But it’s a sobering thought that we are only just beginning to use the first propulsion technology (ion drives) beyond solid and liquid-fuel rockets that have been around for 100 years as a concept for interplanetary travel and for nearly 1000 years as a technology (i.e. Chinese fireworks). While the breakthroughs will come, they won’t come easily.

Tibor will only win his bet under one of two highly unlikely circumstances:

1) We contact ETIs who give us the technology.

2) We discover a practical way to usable wormholes.

Either way, if the odds were good enough (which I doubt they are) I would invest all my retirement savings in betting that Tibor is wrong. As I said before, and interstellar mission due to launch by 2025 would already be in the early planning stages today. Since that’s not happening, then the bet is, to all intends and purposes, already decided.

My guess is that the first interstellar mission, which I assume will be a robotic science probe, will fly with technologies that are as hard for us to imagine

If we start with the assumption of a robotic science probe then this results in a lot of people concluding that an interstellar mission is nearly impossible from an energy and the cost of space-based equipment standpoint.

Is this assumption really necessary?

If instead we drop the science return rationale and choose instead the survival-of-humanity rationale then the resulting technical impossibilities change significantly in our favor.

Near-term propulsion technologies, which are already known, make viable candidates for a 10,000 year mission. That impossibility is significantly reduced. Surviving micrometeorites is easily solved. Imagining funding becomes easier. I think that the rationale for survival is stronger than that for science return.

However, one exchanges the difficulty of propulsion for the difficulty of biotechnology. We need to figure out:
– how frozen embryos can be viable after 10,000 years,
– how gestation can be automated,
– how childrearing can be automated, and
– how life-support producton can be automated.

And this is where we’re at with R&D with no additional interstellar-driven funding. Couldn’t these technologic challenges be readily overcome by ISS-level funding? Also these biotech R&D steps are multiple and relatively small. Extracting He-3 from Jupiter or putting up dozens or hundreds of multi-ton SPSs are pretty expensive steps.

So why talk about impossibilities? Dr. Villard is correct. All we need is a different perspective. And what value can we place on purchasing an insurance policy for humanity?

I’m not convinced the advanced propulsion will be propulsion at all, as we currently think of it.

I’m betting it’s going to be something akin to quantum tunneling, albeit on a macro scale. You wink out at point A, and wink back in at point B, instantly, having crossed the potential barrier without actually passing through it.

All this talk of pushing something (including a region of space) from A to B over a span of time is as antiquated as Buck Rogers.

Now how you perform quantum tunneling on a macro scale, that’s the real challenge, where we need some heavy imagining. Does it involve dark energy, dark matter, M-theory, who knows.

Hey Tibor, thanks for replying. I ought to make it clear that nobody would be more delighted than I if you won the bet. I may be a realist, but will be cheering the professionals on every step of the way.

One question about the bet, though. What happens if, by 2025, we discover a way to open a wormhole to a parallel universe and make contact with another Earth? Who wins the bet then? :)

It is really accurate to say that interstellar flight, even now, is an “apparent impossibility,” even at decent speeds? Most of the best technology we have right now for doing it has been ruled out (particularly nuclear propulsion) for economic and political reasons. There’s a big difference between this situation and not having the technology (or the ability to develop it) altogether. And even if interstellar flight was completely impossible right now, to call it an “impossibility” and leave it at that would probably be as meaningful as Leonardo da Vinci saying that airplanes were impossible. In his time, they definitely were, but that eventually changed, and changed in a relatively short period of time–400 years, less than one-tenth of recorded human history.

In Centauri Dreams, Paul Gilster looks at peer-reviewed research on deep space exploration, with an eye toward interstellar possibilities. For the last eleven years, this site has coordinated its efforts with the Tau Zero Foundation, and now serves as the Foundation's news forum. In the logo above, the leftmost star is Alpha Centauri, a triple system closer than any other star, and a primary target for early interstellar probes. To its right is Beta Centauri (not a part of the Alpha Centauri system), with Beta, Gamma, Delta and Epsilon Crucis, stars in the Southern Cross, visible at the far right (image: Marco Lorenzi).

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